This invention relates to offset printing, and in particular to an offset printing press having a dampening and inking roller-containing carriage linearly movable to and from an associated plate cylinder.
The set of dampening and inking rollers on the carriage, when moved to an engagement position with a respective plate cylinder, must be properly positioned relative to the plate cylinder to provide controlled amounts of inking and dampening fluid to the plate cylinder. To provide such proper positioning, it is necessary that lateral and skewing movements of the linearly movable carriage be eliminated.
The prior art, as represented by U.S. Pat. No. 3,521,559 to Sejeck et al., is intended to provide proper positioning of a linearly movable ink roller-containing carriage relative to its respective plate cylinder by the use of interlocking abutting slide members of wear-resistant, low friction, synthetic resin. The slide members are intended to preclude lateral shifting or skewing of the carriage to provide for proper positioning of the carriage-contained ink rollers relative to their respective plate cylinder. Such a slide arrangement is further intended to give all the benefits of a more expensive machined dovetail slide arrangement.
While the Sejeck et al. slide arrangement may represent a cost improvement over a conventional dovetail type slide, such a slide arrangement would still be susceptible to surface-to-surface sliding friction wear as is a dovetail-type slide. Further, the weight of the moving carriage may have to be limited to prevent degeneration of the relatively soft synthetic resin material used to form the Sejeck et al. carriage-supporting slide members.